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How to Troubleshoot for a Legacy Survey Application Running on ASP.NET 2.0

We built this legacy application back in 2007 and have a major upgrade in 2009 and has been running since then but then there is not much activity since 2014. Then reassure-ct again in late 2015.


Couple findings

Error on the session

This is a bit shocking cause the .cs file is never being changed since 2009 !!!

Solution: Change the code accordingly to handle the missing handling of Session.

Find another one that is related to Debug mode. Set: <compilation debug=”false”> in Web.Config. There is a possibility that there is a bug previously and didn’t set back into False.

Validation of ViewState MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validation key and validation algorithm. AutoGenerate cannot be used in a cluster.

Turn out that the database server is registered under web.config still using the new production server. Need to change to a new server.

The application message came up: “You have a duplicate in MostLeast Preferred section. The option only can be used once of those questions. Please re-select it again.” Check the answer in the application and no duplicate answer.

Turn out that the actual matrix answer records in the database table have a duplicate for that particular question. Looks like entering twice. Not sure causing this at this stage. However, removing the duplicated entries solves the problem.


Photo by Pixabay:

[Notes: Pageviews – 1,175 – before migrated from the Dewalist Blog website on 09/08/2020]



About Author

Valdy founded, a helpdesk and IT Services provider that has taken care of nearly 40,000 customer service requests in the past 15 years - nearly 2,600 per year. He also created the growing - a classified website that has close to 110,000 page views and 9,000+ user visits per month with 61,000+ yearly published ads and 47,000 active registered users. He blogs for the ever-growing, a tech blog that gets around 20,000 impressions per month with 700 clicks and 10 average pages first impressions on Google Search. You can reach him on the Contact Us page, social media links below or

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